How can Blender automatically update a 3d model from a changing network file
Old question I know, but I've written an addon for 2.9 which, in combination with a networked filesystem and assuming the model is in .blend format, should be able to achieve this:
https://github.com/gandalf3/auto-reload-linked-libraries/releases
The basic usage would be something like:

Put the shared file on the networked filesystem
Install and enable the addon
Link the desired datablocks from the shared file
Make changes to the shared file; changes should appear in blender more or less instantly.

That said it's not perfect (I just threw it together to work well enough for my purposes, but if you run into issues I wouldn't mind trying to improve it), and there's no prompt before reloading.